Hair loss or Alopecia in its various forms is a global widespread problem for both men and women. Androgenetic alopecia (AGA) may affect up to 70% of men and 40% of women at some point in their lifetime. While men typically present with a distinctive alopecia pattern involving hairline recession and vertex balding, women normally exhibit a diffuse hair thinning over the top of their scalps. The treatment standard in dermatology clinics continues to be minoxidil and finasteride with hair transplantation as a surgical option.
Alopecia areata (AA) is the patchy loss of hair on the scalp or body. It can occur at any age and affects 1% of the population, most commonly children. The reasons for its development are not fully understood. Although not life threatening, the hair loss can be psychologically traumatic. Scientists think AA is an autoimmune disease where white blood cells from the immune system attack hair follicles and keep them from producing hairs. Autoimmune diseases occur when a human's immune system mistakenly thinks that part of his or her own tissue is diseased. The tissue is then attacked. The end result depends on how effectively the tissue defends itself as it tries to grow back normally. Treatment depends on the extent of the disease, and the age of the patient. For small disease patches, intralesional steroid injections (Kenalog®) are the best approach. This is injected with a tiny needle directly into the patches on the scalp with injections spread over affected areas. Injections are repeated every 4 to 6 weeks. The amount of steroid used is safe as long as reasonable limits are not exceeded. Other options include topical minoxidil (Rogaine) and prescription steroid lotions. These are better for moderately extensive cases.
For more severe widespread disease, options include short contact anthralin treatment (Micanol) and contact hypersensitization. The most effective treatment currently available is contact hypersensitization with some studies showing a 40% success rate. It causes local dermatitis (rash) with swollen lymph nodes. Treatment needs to be continued from months to a year or so to get a good result.
Each hair sits in a cavity in the skin called a follicle. The average human head has about 100,000 hair follicles. Each follicle can grow about 20 individual hairs in a person's lifetime. Hair grows about an inch (2.54 cm) every couple of months. Each hair grows for 2 to 6 years, remains at that length for a short period, then falls out. Most people shed 50 to 150 hairs a day. A new hair soon begins growing in its place.
The hair follicle cycle consists of stages of rest (telogen), hair growth (anagen), follicle regression (catagen), and hair shedding (exogen). The entire lower epithelial structure is formed during anagen, and regresses during catagen. The transient portion of the follicle consists of matrix cells in the bulb that generate seven different cell lineages, three in the hair shaft, and four in the inner root sheath (IRS), see FIG. 1.
The typical pattern of male baldness begins at the hairline. The hairline gradually moves backward (recedes) and forms an “M” shape. Eventually, the hair becomes finer, shorter, and thinner, and creates a U-shaped (or horseshoe) pattern of hair around the sides of the head.
Medications that treat male pattern baldness include:                Minoxidil (ROGAINE), a solution that is applied directly to the scalp to stimulate the hair follicles. It slows hair loss for many men, and some men grow new hair. Hair loss returns when you stop using this medicine.        Finasteride (PROPECIA, PROSCAR), a pill that interferes with the production of a highly active form of testosterone that is linked to baldness. It slows hair loss. It works slightly better than minoxidil. Hair loss returns when you stop using this medicine.Hair transplants consist of removing tiny plugs of hair from areas where the hair is continuing to grow and placing them in areas that are balding. This can cause minor scarring and possibly, infection. The procedure usually requires multiple sessions and may be expensive.        
Suturing hair pieces to the scalp is not recommended. It can result in scars, infections, and an abscess of the scalp. The use of hair implants made of artificial fibers was banned by the FDA because of the high rate of infection.
Although the mechanism is not clearly understood, genetics and hormones are thought to be involved in pattern baldness. In pattern baldness, heredity appears to play a significant role as pattern baldness on either side of the family increases the risk of balding. Excessive amounts of a hormone known as dihydrotestosterone (“DHT”) is also thought to adversely affect hair follicles. DHT binds to androgen receptors in the hair follicles to regulate normal hair growth. Testosterone, a hormone that is present in high levels in males after puberty, is converted to DHT by an enzyme called 5-alpha reductase. As men mature, their bodies produce more testosterone resulting in increased amounts of DHT. Androgen receptor activity increases, slowing down hair production and producing weaker, shorter hair each time the hair regrows.
Other causes of temporary hair loss include disease, diabetes, lupus and thyroid disorder, poor nutrition, medications, certain drugs, medical treatments, childbirth, hair treatments and scalp infections.
Baldness, whether permanent or temporary, cannot be cured, but treatments are available to help promote hair growth or hide hair loss. However, results vary and side effects can be disconcerting.
Minoxidil (ROGAINE), available over-the-counter, is a liquid that is dispensed onto the scalp twice daily to regrow hair and to prevent further loss. Some people experience some hair regrowth, a slower rate of hair loss, or both. However, new hair resulting from minoxidil use may be thinner and shorter than previous hair. In addition, side effects can include irritation of the scalp.
Finasteride (PROPECIA) is a prescription medication used to treat male-pattern baldness taken daily in pill form. Finasteride inhibits the production of the male hormone dihydrotestosterone. Many people taking finasteride experience a slowing of hair loss, and some may show some new hair growth. Results may take up to several months to manifest. Side effects may include diminished sex drive and sexual function. In addition, Finasteride is not approved for use by women. In fact, it poses significant danger to women of childbearing age and should not be handled by pregnant women.
Surgical procedures, such as hair transplants and scalp reduction surgery, have also been used to treat hair loss. Hair transplants involve taking tiny plugs of skin, each containing one to several hairs, and implanting them into the balding areas. However, effective treatment may require several sessions. Scalp reduction involves decreasing the area of bald skin by surgically removing a balding area and closing the gap with hair-covered scalp. However, these surgical procedures are expensive, can be painful, and may require several procedures. In addition, risks include infection and scarring.
Thus, a safe, effective, cost-effective, easy treatment for preventing hair loss or promoting hair growth is still needed.